合并列表（操作字典）

dic的排序方法参考：
https://blog.csdn.net/Eric_LH/article/details/77429740
https://www.cnblogs.com/Renqy/p/12786603.html

import sys
l = [d.strip('\n') for d in sys.stdin.readlines()]
n = int(l[0])
dic = {}
# for i in range(1,n+1):
#     key_value = list(map(int,l[i].split()))
#     #print(key_value)
#     if key_value[0] not in dic: #判断key是否存在于字典中，不在的话，直接dic[index]插入key
#         dic[key_value[0]] = key_value[1]
#     elif key_value[0] in dic:
#         dic[key_value[0]] += key_value[1]
# for j in sorted(dic):
#     print(j,dic[j])
    
for i in range(1,n+1):
    key_value = list(map(int,l[i].split()))
    dic[key_value[0]] = dic.get(key_value[0],0) + key_value[1] #get函数获取某个key的值，若key不存在，返回第二个参数
for j in sorted(dic):
    print(j,dic[j])